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Ventilation System for Torus Blasting and Re-coating Project

Project Scope:

  • Personnel protection.
  • Prevention of a release to the environment.
  • Maintain air quality during blasting operations and cleanup.
  • Maintain optimal conditions for coating applications and curing.


  • Air is removed from the torus and negative pressure is maintained at 0.02 - 0.05 in wg to prevent a release to the torus room and drywell.
  • Air taken from the torus enters the high-efficiency pre-filters.
  • Two ventilation ducting runs bring pre-filtered air from the torus to the junction box.  The air is then routed to three ventilation units through isolation dampers.  Two HEPA units are used to move 16,000 cfm and a third unit is connected as a spare.
  • Clean bleed-air is discharged through two activated carbon adsorbers downstream of the HEPA filtration units.
  • Cleaned air is returned to the torus.
  • Dehumidification is used to establish conditions for coating application.  HEPA-filtered air is directed to dehumidifiers.  To maintain torus negative pressure, a smaller amount of air is discharged to the atmosphere through charcoal adsorbers.
  • Air returning to the torus is either cooled (using chilled water) or heated (using electric heaters) to achieve the desired temperature.  Cleaned and temperature-adjusted air is returned to the torus.  Directional air-discharge adapters send the air around the torus to the air filters on the opposite side.
  • A ventilated enclosure houses the blast-media reclamation station.